Chuntao Jiang

With the continuous development of complex marine hydrocarbon reservoirs, broadband seismic data have shown growing advantages in revealing abundant stratigraphic information. Affected by acquisition conditions and stratigraphic attenuation, the acquired seismic data commonly suffer from narrow bandwidth, and conventional broadband processing techniques are incapable of optimizing the overall frequency band. This study proposes a coordinated high- and low-frequency broadband compensation method based on adaptive weight fusion to effectively extend the frequency bandwidth of seismic data. Firstly, wavefield separation is used to suppress ghost reflections, compensate low-frequency effective signals, and restore the continuity of the low-frequency spectrum. Then, based on the spectrum extrapolation method of maximum entropy spectrum estimation, a spectrum prediction model is established to achieve the continuation of high-frequency effective signals. Finally, in combination with the signal-to-noise ratio of each frequency band, the adaptive weight fusion algorithm is applied for weighted summation. The acquired broadband seismic data feature a continuous spectrum and balanced energy, greatly improving seismic imaging quality. Comparative results obtained using conventional processing methods verify that the proposed method can significantly improve stratigraphic continuity and wave group characteristics.

Research on seismic wave propagation in fluid-bearing reservoirs is crucial for unconventional oil and gas exploration. While traditional wave equation-based simulations are well-established, they often struggle to accurately model fluid-solid two-phase media characterized by complex tectonic features, strong discontinuities, and intricate interfacial couplings. This paper presents an advanced approach utilizing two mesoscopic discrete models: the lattice spring model (LSM) and the lattice Boltzmann model (LBM). The LSM simulates solid wavefields via the velocity Verlet algorithm, with optimized spatial distributions of springs and masses. Concurrently, the LBM is employed for fluid wavefield simulation, featuring a precisely designed lattice model and well-defined collision and streaming rules. In particular, a novel momentum exchange strategy incorporating the inverse squared distance method (ISDM) is constructed to enhance wavefield information transfer between the LSM and LBM at fluid-solid boundaries, aiming to improve accuracy and stability. The efficacy of the novel ISDM-LSM-LBM coupling algorithm is validated through simulations of layered models, fluid-filled cavity model, and river filling models. Compared to the original LSM-LBM algorithm, it exhibits enhanced computational accuracy and stability, albeit with a modest increase in computational burden and memory consumption. Comparative analysis with finite difference method (FDM) results reveals that the ISDM-LSM-LBM algorithm accurately captures wavefield characteristics. Although slight differences are observed in the depiction of reflected, transmitted, and converted waves at internal boundaries—attributable to the distinct fluid-solid interface treatments of each method—the new algorithm’s flexibility in boundary coupling and consideration of additional interaction forces offer significant improvements in accuracy and stability. This innovative simulation technique, independent of traditional wave equations, significantly enhances the precision and adaptability of wavefield calculations in fluid-solid media, providing substantial benefits for oil and gas geophysical exploration.

When the structure of the media is complex or there are strong interfaces, the simulated seismic waves obtained by the traditional forward modeling methods are often difficult to fit the real wavefields. To get more accurately simulated waves, in this paper, we utilize the widely used three-dimensional (3D) lattice Boltzmann model (LBM) in fluid mechanics as a new tool for seismic wavefield simulation. In order to establish a general framework for the LBM in the 3D case, firstly, we introduce an improved LBM scheme in 3D form considering the reflection and transmission effects. Then, we carry out a systematic dispersion analysis of the LBM with different lattices by analogizing the dispersion derivation of the finite-difference method (FDM), and comparing the results of the LBM with those of the FDM. Finally, we explore the stability conditions and present the treatment of initial and boundary conditions. To verify the feasibility of this 3D-LBM strategy, we perform 3D wavefield simulation tests on a homogeneous model, a cavity model, and a five-layer model, respectively. By comparing the results obtained by LBM and FDM, we conclude that the accuracy of this improved LBM scheme is acceptable. This 3D-LBM modeling scheme provides a new option for seismic wavefield simulation for complex media thanks to its flexibility of boundary processing and efficient parallelism capability.